Dell PowerVault 725N (Rackmount NAS Appliance) - Manual (Page 135)

Storing Persistent Images
You can configure the NAS system to store a maximum of 250 persistent images per system; however, if you exceed the maximum, the oldest persistent image
with the lowest retention weight is overwritten. This number of persistent images allows you to schedule multiple persistent images. (You should tailor your
schedule depending on how the data is changing.) For example, you could implement a schedule similar to the following schedule:
l Seven daily persistent images with a high priority
l Two weekly persistent images with a medium priority
l Two monthly persistent images with a low priority
This type of schedule gives you good snapshot coverage and ensures that your most recent data has the highest priority.
Configuring the Persistent Image Global Settings
You can modify the various aspects of the persistent image environment by performing the following steps:
1. Log in to the NAS Manager.
2. Click Disks.
3. Click ActiveArchive.
4. Click Global Settings.
5. Configure the following options.
l Maximum persistent images — Specifies the maximum number of active persistent images per system, up to a maximum of 250. When the
system has 250 persistent images stored, starting another persistent image overwrites the oldest persistent image with the lowest retention
weight.
l Inactive period — Prior to starting a persistent image, the system waits for a period of relative inactivity on the volume being imaged. The
default value for this period, which is 5 seconds, allows systems to start an image with a consistent file set and a minimal time-out. Experienced
administrators may reduce or increase this value for system optimization. Reducing the inactive period allows persistent images to begin on
systems where disk inactivity is rare, at the possible expense of synchronization problems within applications that are concurrently writing to
multiple files.
l Inactive time-out — Specifies the amount of time the system continues to retry to create a persistent image (default time is 15 minutes). A
persistent image cannot start until a period of relative inactivity, specified by Inactive period, occurs. If an interval longer than Inactive time-out
passes before the persistent image can begin, the persistent image cannot be taken and an error is displayed in the NAS Manager status
indicator and logged in the event log.
l Image directory — Specifies the directory name that is to be used for the persistent image mount point. Each persistent image appears as a
subdirectory in the volume that is being imaged. The entire content of the volume, as it existed when the persistent image was created, appears
under this directory.
6. If you need to re-establish the system defaults, click Restore Defaults.
7. Click OK to update the global settings.
Configuring Persistent Image Volume Settings
You can modify volume settings by performing the following steps:
1. Log in to the NAS Manager.
2. Click Disks.
3. Click ActiveArchive.
4. Click Volume Settings.
5. Select the volume that you want to reconfigure.
6. Click Configure.
7. Use the appropriate menus to configure the following options.
NOTE: Before changing the image directory name, you must delete all existing persistent images.